When calcium is in it's pure form it is a shiny, and metallic. Luckily the form we take in isn't pure. Usually we take in calcium from milk or vegetables. If you do not get enough calcium in your body you have a likely chance of Osteoporosis. This is a disease where the bones get thin and easily break. Calcium phosphide of calcium is extremely poisonous to plants.

http://www.dairy.com.au/consumers/images/dairyaustralia/agda_07_riverina_milk.jpg
http://www.dairy.com.au/consumers/images/dairyaustralia/agda_07_riverina_milk.jpg
http://www.germes-online.com/direct/dbimage/10251327/Vegetables.jpg
http://www.germes-online.com/direct/dbimage/10251327/Vegetables.jpg